Heat exchanger having laminated tubes

ABSTRACT

A heat exchanger has a pair of heat exchanging parts composed of laminated tubes. Each tube is composed of a pair of metal sheets joined to each other. Locating parts each having a projecting piece and a recess are arranged on respective sides of the metal sheet. When the metal sheets are mated, the projecting pieces are engaged with the recesses, respectively. Moreover, the metal sheets are in inverse relation to each other about a top-and-back inversion axis and the projecting pieces are arranged symmetrically to the recesses about the top-and-back inversion axis.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat exchanger having laminated tubeswhich are composed of a pair of metal sheets joined to each other,respectively.

2. Description of the Related Art

Japanese Patent Application Laid-open No. 2000-105091 discloses a heatexchanger having laminated tubes which are composed of a pair of metalsheets joined to each other.

In recent years, there has been requirement of miniaturization for heatexchangers for vehicles. With the requirements, it has been furtherrequired to make a heat exchanger thin in the draft direction. Thus, inthe conventional heat exchanger, there was an attempt to narrow weldformed on the peripheral margins of the metal sheets in pairs.

However, the narrowing of such weld causes the possibility of increasingdefects in welding the metal sheets in pairs in the production of a heatexchanger. Also noted that even if a heat exchanger has only one weldingdefect in one metal sheet, then the whole heat exchanger is regarded asa defective product, thereby incurring waste. In order to produce nodetects in the production of heat exchangers, it is necessary to improvethe management of assembling accuracy in the metal sheets in pairs,causing the manufacturing cost to be elevated.

SUMMARY OF THE INVENTION

In the above-mentioned situation, it is an object of the presentinvention to provide a heat exchanger having a plurality of tubes eachof which has a pair of metal sheets and which is formed by reversing onemetal sheet to overlap on the other metal sheet and further welding themetal sheets to each other, the heat exchanger being capable ofnarrowing the weld of the metal sheets with an improvement of theassembling accuracy of the metal sheets while suppressing a rise in themanufacturing cost as possible.

In order to attain the above object, the first aspect of the inventionprovides a heat exchanger, comprising: a heat exchanging part includinglaminated tubes each of which has a pair of metal sheets joined to eachother, each of the tubes having heat exchanging passage formed thereinto extend along the longitudinal direction of the tube, and cylindricaltank parts formed at both ends of each heat exchanging passage toproject from a main body of the tube, the cylindrical tank parts of theadjoining tubes connected with each other in communication with eachother, wherein the metal sheets have at least one top-and-back inversionaxis about which one metal sheet is in inverse relation to the othermetal sheet, and wherein each metal sheet has a plurality of projectingpieces formed on the outer circumferential edge of the metal sheet so asto project toward a mate to the metal sheet and a plurality of recessesformed on the outer circumferential edge of the metal sheet so as toallow the projecting pieces to be inserted thereinto respectively, theprojecting pieces being respectively arranged symmetrically to therecesses about the top-and-back inversion axis, thereby the projectingpiece and the recess constituting a locating part when the metal sheetsare mated, the locating parts are provided on at least respective sidesof the metal sheet, respectively.

In the heat exchanger of the first aspect, since the locating partswhere the projecting pieces engage in the recesses when the metal sheetsin pairs are laid to overlap on each other are provided on therespective sides of the outer circumferential edges of the metal sheets,it is possible to improve the assembling accuracy of the metal sheetsand also possible to make the weld small thereby realizing a thin heatexchanger. Moreover, since the metal sheets have at least onetop-and-back inversion axis about which one metal sheet is in inverserelation to the other metal sheet, and the projecting pieces beingrespectively arranged symmetrically to the recesses about thetop-and-back inversion axis, it is possible to form the pair of metalsheets having an identical configuration. Thus, in spite of theprovision of the projecting pieces and the recesses in view of theimprovement in assembling accuracy, it is unnecessary to prepare metalsheets of different configurations, whereby the rise in manufacturingcost can be avoided.

In a preferred embodiment, the top-and-back inversion axis comprises acenter line of the metal sheet in a longitudinal direction of the metalsheet. Further, the top-and-back inversion axis comprises a center lineof the metal sheet in a direction perpendicular to a longitudinaldirection of the metal sheet.

With the arrangement, when one metal is reversed about the center lineof the metal sheet in a longitudinal direction or a directionperpendicular to the longitudinal direction of the metal sheet, themetal sheet can be mated to the other metal sheet accurately. Thereforethis heat exchanger is superior in terms of its versatility. Thelaminated tubes constitute a pair of heat exchanging parts which arearranged side by side.

The heat exchanger comprises an inner fin which is disposed in the heatexchanging passage formed in the tube, wherein the projecting piece inat least one of the locating parts has a dimension in which a leadingend thereof can pass through the recess at mating.

In this configuration, it is possible to fix one pair of metal sheetswith each other preliminarily by crimping the projecting piece.Therefore, even if an inner fin is disposed in the metal sheets in sucha preliminarily fixed state, it is possible to prevent an occurrence ofdisplacement of the inner fin in the tube.

The projecting pieces in the locating parts allocated on at leastopposing sides of the metal sheets have a dimension in which respectiveleading end thereof can pass through the recess at mating.

Also in this configuration, it is possible to fix one pair of metalsheets with each other preliminarily by crimping the projecting piece atthe locating parts on the opposing sides of the metal sheets. Therefore,it is possible to prevent the occurrence of displacement of the innerfin more certainly.

The metal sheet has a substantially rectangular shape in plan view, andthe projecting pieces in the locating parts allocated on both long sidesof the rectangular-shaped metal sheet have a dimension in whichrespective leading end thereof can pass through the recess at mating.

Also in this configuration, it is possible to fix one pair of metalsheets with each other preliminarily by crimping the projecting piece atthe locating parts on both long sides of the rectangular-shaped metalsheets. Therefore, it is possible to prevent the occurrence ofdisplacement of the inner fin certainly in comparison with a case thatthe metal sheets are preliminarily fixed with each other at the locatingparts on respective short sides of the rectangular-shaped metal sheets.

The projecting pieces in the all locating parts have a dimension inwhich respective leading end thereof can pass through the recesses.

In this configuration, it is possible to fix one pair of metal sheetswith each other preliminarily by crimping the projecting piece at all ofthe locating parts. Therefore, it is possible to prevent the occurrenceof displacement of the inner fin certainly.

The metal sheet has a substantially rectangular shape in plan view, andis two or more locating parts are arranged on each long side of themetal sheet.

Then, owing to the provision of two or more locating parts on each longside of the metal sheets, it is possible to improve the positioningaccuracy of the metal sheets. Further, when the projecting pieces arecrimped, the occurrence of displacement of the inner fin can beprevented certainly.

These and other objects and features of the present invention willbecome more fully apparent from the following description and appendedclaims taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a heat exchanger (evaporator) in accordancewith the first embodiment of the present invention, also viewed from itsupwind side;

FIG. 2 is a top view of the evaporator of FIG. 1;

FIG. 3 is a side view of the evaporator of FIG. 1, on the light side inthe width direction of the evaporator;

FIG. 4 is a side view of the evaporator of FIG. 1, on the left side inthe width direction of the evaporator;

FIGS. 5A to 5D are various views of a side plate of the evaporator ofFIG. 1, on the left side in the width direction of the evaporator: FIG.5A is a plan view of the side plate, FIG. 5B a view of the side plateviewed in the direction of arrow 5B of FIG. 5A, FIG. 5C a view of theside plate viewed in the direction of arrow 5C of FIG. 5A and FIG. 5D aview of the side plate viewed in the direction of arrow 5D of FIG. 5A;

FIGS. 6A to 6D are various views of another side plate of the evaporatorof FIG. 1, on the right side in the width direction of the evaporator:FIG. 6A is a plan view of the side plate, FIG. 6B a view of the sideplate viewed in the direction of arrow 6B of FIG. 6A, FIG. 6C a view ofthe side plate viewed in the direction of arrow 6C of FIG. 6A and FIG.6D a view of the side plate viewed in the direction of arrow 6D of FIG.6A;

FIGS. 7A to 7D are various views of a first metal sheet forming a tubeof the evaporator of FIG. 1: FIG. 7A is a plan view of the first metalsheet, FIG. 7B a view of the first metal sheet viewed in the directionof arrow B of FIG. 7A, FIG. 7C a view of the first metal sheet viewed inthe direction of arrow C of FIG. 7A and FIG. 7D a view of the firstmetal sheet viewed in the direction of arrow D of FIG. 7A;

FIGS. 8A to 8D are various views of a second metal sheet forming a tubeof the evaporator of FIG. 1: FIG. 8A is a plan view of the second metalsheet, FIG. 8B a view of the second metal sheet viewed in the directionof arrow 8B of FIG. 8A, FIG. 8C a view of the second metal sheet viewedin the direction of arrow 8C of FIG. 8A and FIG. 8D a view of the secondmetal sheet viewed in the direction of arrow 8D of FIG. 8A;

FIG. 9A is an exploded perspective view of the tube, showing itslamination and FIG. 9B is a perspective view of the tube in itsassembled state;

FIG. 10A is a sectional view of one pair of metal sheets before beingcrimped and FIG. 10B is a sectional view of the metal sheets after beingcrimped;

FIG. 11 is a sectional view of a tank part of the tubes, showing itslamination;

FIG. 12 is a schematic view of the evaporator, showing the flow ofcoolant therein;

FIG. 13A is a schematic view showing the distribution of liquid-phasecoolant in two heat exchanging parts (evaporator parts) and FIG. 13B isa schematic view showing the distribution of liquid-phase coolant in theevaporator parts in combination;

FIG. 14 is a perspective view showing a modification of the metal sheetsforming a tube of the evaporator of the first embodiment of the presentinvention;

FIG. 15 is a perspective view showing the metal sheets forming a tube ofthe evaporator of the second embodiment of the present invention; and

FIG. 16 is a perspective view showing the metal sheets forming a tube ofthe evaporator of the third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to accompanying drawings, embodiments of the present inventionwill be described below.

[1^(st). Embodiment]

FIGS. 1 to 13B show the first embodiment of the present invention.According to the first embodiment of the invention, a heat exchanger isembodied by an evaporator 1 interposed in a refrigeration cycle of anautomotive air conditioner. In arrangement, the evaporator 1 ispositioned in an air-conditioner casing inside an instrument panel of avehicle to carry out heat exchange between coolant flowing in theevaporator and air passing through the outside of the evaporator. Due tothis heat exchange, the coolant is evaporated to cool down the air.

First of all, the whole structure of the evaporator 1 will be describedwith reference to FIG. 12.

The evaporator 1 includes two heat exchanging parts 10, 20 juxtaposed onupwind and downwind sides, respectively.

The “downwind-side” heat exchanging part 10 has an upper tank 11, alower tank 12 and a plurality of heat exchanging passages between thetanks 11 and 12. These heat exchanging passages are also communicatedwith the tanks 11, 12. Similarly, the “upwind-side” heat exchanging part20 has an upper tank 21, a lower tank 22 and a plurality of heatexchanging passages between the tanks 21 and 22. As well, these heatexchanging passages are communicated with the tanks 21, 22.

In the downwind-side heat exchanging part 10, the upper tank 11 ispartitioned to a first upper tank part 11 a and a second upper tank part11 b by a partition 14, while the lower tank 12 is partitioned to afirst lower tank part 12 a and a second lower tank part 12 b by apartition 15. The upper tank 11 is provided, on its right side, with anevaporator inlet 7. The stacked heat exchanging passages are dividedinto a first path 10 a, a second path 10 b and a third path 10 c inorder from the right. Consequently, the coolant introduced into thedownwind-side heat exchanging part 10 via the evaporator inlet 7 flowsthrough the first upper tank part 11 a, the first path 10 a, the firstlower tank part 12 a, the second path 10 b, the second upper tank part11 b, the third path 10 c and the second lower tank part 12 b, in thisorder. Then, the coolant is introduced from the most downstream side(i.e. the second lower tank part 12 b) of the downwind-side heatexchanging part 10 into the most upstream side (i.e. the first lowertank part 22 a) of the upwind-side heat exchanging part 20 through acommunication passage 9. That is, the downwind-side heat exchanging part10 constitutes an “inlet-side” heat exchanging part on the upstream sideof the coolant's flow, while the upwind-side heat exchanging part 20constitutes an “outlet-side” heat exchanging part on the downstream sideof the coolant's flow.

In the upwind-side heat exchanging part 20, the lower tank 22 ispartitioned to a first lower tank part 22 a and a second lower tank part22 b by a partition 24, while the upper tank 21 is partitioned to afirst upper tank part 21 a and a second upper tank part 21 b by apartition 25. The upper tank 21 is provided, on its light side, with anevaporator outlet 8. The stacked heat exchanging passages are dividedinto a first path 20 a, a second path 20 b and a third path 20 c inorder from the light. Consequently, the coolant introduced into theupwind-side heat exchanging part 20 via the communication passage 9flows through the first lower tank part 22 a, the first path 20 a, thefirst upper tank part 21 a, the second path 20 b, the second lower tankpart 22 b, the third path 20 c and the second upper tank part 21 b, inthis order. Then, the coolant is discharged from the evaporator 1through the evaporator outlet 8 on the right side of the second uppertank part 21 b as the most downstream part of the upwind-side heatexchanging part 20 on the outlet-side of the coolant's flow.

In the evaporator 1, the heat exchanging parts 10, 20 are each dividedinto the plural paths (e.g. three paths each in the shown example, thatis, the paths 10 a, 10 b, 10 c and the paths 20 a, 20 b, 20 c) so as tohave the same reference number in each of the parts 10, 20. Further, inthe opposing paths overlapped on both “upwind” and “downwind” sides (forexample, the first path 10 a of the part 10 and the third path 20 c ofthe part 20), the flowing directions of the coolant therein are oppositeto each other, vertically and horizontally, including the coolant'sflows in the tank parts on the upstream and downstream sides of theopposing paths. With this coolant's passage structure mentioned above,when superimposing the heat exchanging part 10 on the heat exchangingpart 20 along the draft direction, it is possible to eliminate anexchanger area where the liquid-phase coolant L does not flow, as shownin FIGS. 13A and 13B. As a result, the evaporator 1 can be provided witheven distribution in temperature and high efficiency in heat exchange.

The constituents of the evaporator 1 (i.e. tubes 30, side plates 34, 35and piping connectors 36, etc.) will be described below.

As shown in FIGS. 1 to 4, the evaporator 1 of this embodiment includes aplurality of tubes 30 stacked on each other and a plurality of outerfins 33 each interposed between the adjoining tubes 30. Each tube 30 isprovided by reversing one metal sheet 40 (40A), further overlapping iton another metal sheet 40 (40B) and further welding the periphery of thesheet 40A to the periphery of the sheet 40B while forming coolantpassages in the tube 30. Further, the evaporator 1 is provided, on theoutermost sides in the laminating direction of the tubes 30, with sideplates 34, 35 for reinforcement, providing a designated configuration.

As shown in FIGS. 3, 6A, 6B, 6C and 6D, the side plate 34 is providedwith a communication port 34 a communicating with the most upstream part(the first upper tank part 11 a) of the heat exchanging part 10 andanother communication port 34 b communicating with the most downstreampart (the second upper tank part 21 a) of the heat exchanging part 20. Apiping connector 36 forming the inlet 7 and the outlet 8 of theevaporator 1 is attached to the communication ports 34 a, 34 b. Theother side plate 35 (see FIGS. 4 and 5A to 5D) has a communicationpassage 9 formed integrally to communicate the most downstream part ofthe part 10 (i.e. the second lower tank part 12 b) with the mostupstream part of the part 20 (i.e. the first lower tank part 12 a).Noted that reference numerals 35 b denote reinforcing protrusion partsformed on the side plate 35, while reference numeral 37 denotes areinforcing plate which is fitted to the side plate 34 to form a coolantpassage and arranged between the side plate 34 and the piping connector36.

The constitution of the tube 30 will be described below.

FIG. 9A is an exploded perspective view of the tube 30, showing itslamination. FIG. 9B is a perspective view of the tube 30 in itsassembled state. FIGS. 7A to 7D show the metal sheet 40 (40A or 40B)forming the tube 30. As shown in FIG. 7A, the metal sheet 40 is shapedto be substantially rectangular in plan view. In noted that the metalsheet 40A has a configuration identical to that of the metal sheet 40B.The metal sheet 40B corresponds to an element that can be obtained byturning over R the metal sheet 40A about a “top-and-back” inversion axisX, and vice versa. The metal sheets 40A and 40B are mated to form thetube 30.

The tube 30 is provided with heat exchanging passages 31, 31 thatperform heat exchange between the coolant flowing in the passages 31, 31and air flowing outside the tube 30. The heat exchanging passages 31, 31are formed by one heat exchanging passage 31 for the “downwind-side”heat exchanging part and another heat exchanging passage 31 for the“upwind-side” heat exchanging part. On both ends of the tube 30 in thelongitudinal direction, cylindrical tank parts 32, 32 are formed so asto project from the both ends of each heat exchanging passage 31 to theoutside. That is, each of the metal sheets 40A, 40B forming the tube 30includes two grooves 41, 42 for a heat-exchanging passage, extendingalong the longitudinal direction and four tank parts 43, 44, 45, 46.

A plurality of projecting pieces 47 and recesses 48 are formed in theouter circumference of the metal sheet 40. The projecting pieces 47 andthe recesses 48 are symmetrically arranged about the top-and-backinversion axis X. That is, if making the metal sheet 40A opposing themetal sheet 40B, then the projecting pieces 47 oppose the recesses 48respectively. Subsequently, when overlapping the metal sheet 40A on themetal sheet 40B, the projecting pieces 47 are inserted into the recesses48, so that the resulting engagements between the projecting pieces 47and the recesses 48 allow the metal sheets 40A, 40B to be located toeach other. These locating elements having the projecting pieces 47 andthe recesses 48 in engagement are provided on respective sides 40 a, 40b, 40 c, 40 d of the metal sheet 40 (or the tube 30).

According to the embodiment, all of the projecting pieces 47 are shapedwith dimensions so that their leading ends pass through the recesses 48when fitting the metal sheet 40A to the metal sheet 40B whileinterposing two inner fins 61, 61 therebetween. Subsequently, as shownin FIGS. 10A and 10B, the crimping of the projecting pieces 47 allowsthe metal sheets 40A, 40B to be caulked thereby fixing the tube 30preliminarily.

It is noted in the shown embodiment that the above top-and-backinversion axis X is identical to a sheet's center line extending alongthe direction perpendicular to the longitudinal direction of the metalsheet 40, namely, a center line for dividing the metal sheet 40 into twoequal parts in the longitudinal direction of the sheet 40.

In the manufacturing process (see FIG. 9) of the evaporator 1, the tubes30 in such a preliminarily fixed condition are laid to overlap on eachother into a preliminary assembly as shown in FIGS. 1 to 4. Thereafter,the preliminary assembly is carried by a not-shown jig and transferredinto a furnace for welding the preliminary assembly. Noted that FIGS. 9Aand 9B do not illustrate the outer fin 33 for convenience ofunderstanding. According to the above-mentioned manufacturing process,if possible to position the adjoining tubes 30, then it becomes possibleto automatize the laminating operation of the tubes 30, whereby themanufacturing cost can be saved. That is, the possibility of positioningthe metal sheets 40A, 40B in their addorsed (back-to-back) conditionwould allow the laminating operation of the tubes 30 to be automatedthereby reducing the manufacturing cost of the evaporator 1. Therefore,as shown in FIGS. 7A and 7B, in the tank parts 43, 44 (45, 46) on bothsides of the groove 41 (42), one tank part 43 (46) is provided, on theperiphery of its opening end 43 a (46 a), with an engagement projection49 as locating parts (locating means). Owing to the provision, when theengagement projection 49 of the tank part 43 (46) is inserted into theopening end 44 a (45 a) of the other tank part 44 (45), the metal sheets40A, 40B in their addorsed (back-to-back) can be positioned in relationwith each other. In other words, the metal sheets 40 (40A, 40B) arerespectively shaped so as to be symmetrical to each other about thetop-and-back inversion axis X except the projecting pieces 47, therecesses 48 and the engagement projection 49.

Also noted that not only the metal sheet 40 of FIGS. 7A and 7B but asecond metal sheet 50 of FIGS. SA and 8B is employed in this embodiment.The second metal sheet 50 is provided with an “intecral-molding”partition 51 serving as one of the aforementioned partitions 14, 15, 24,25 (see FIG. 12) for dividing the heat exchanging parts 10, 20 into thepaths 10 a, 10 b, 10 c, 20 a, 20 b and 20 c. It is noted that this metalsheet 50 is nothing but a metal sheet where one tank part 43 in the fourtank parts 43, 44, 45, 46 of the first metal sheet 40 is replaced by thepartition 51. Depending on the position(s) of the second metal sheet(s)50 to be inserted into a lamination of the tubes 30, thecompartmentalization of these paths 10 a, 10 b, 10 c, 20 a, 20 b and 20c is determined in the heat exchanging parts 10, 20. Note, in FIGS. 1and 2, reference numerals 50A, 50B, 50C, 50D denote the same metalsheets 50 though some of them are inverted inside and out in thearrangement of the heat exchanger.

The effects of the first embodiment will be summarized below.

First of all, it should be noted that the metal sheets 40A, 40B arerespectively provided, around their outer circumferential edges, withthe projecting pieces 47 projecting toward the reverse side of eachmetal sheet and the recesses 48 allowing insertion of the projectingpieces 47 and that the locating parts each having the projecting piece47 and the recess 48 in combination are provided on the sides 40 a, and40 d of each metal sheet 40A (40B), respectively. Therefore, theassembling accuracy of one pair of metal sheets 40A, 40B is so improvedas to make their weld smaller, whereby it is possible to make the heatexchanger 1 thin.

Moreover, it is noted that each of the metal sheets 40A, 40B is shapedso as to be symmetrical about the top-and-back inversion axis X that isa center line of the metal plate 40A (40B) alone the directionperpendicular to the longitudinal direction and that the projectingpieces 47 are arranged in symmetry with the recesses 48 about thetop-and-back inversion axis X. Therefore, it is possible to form themetal sheet 40A and the metal sheet 40B of identical configurations.Thus, in spite of the provision of the projecting pieces 47 and therecesses 48 in order to improve the assembling accuracy, it isunnecessary to prepare metal sheets of difference configurations,whereby the rise in manufacturing cost can be avoided.

Second, since all of the projecting pieces 47 are formed so that theirleading ends pass through the recesses 48 respectively at all of thelocating parts each having the projecting piece 47 and the recess 48 inengagement, it is possible to preliminarily fix the metal sheets 40A,40B with each other by folding (crimping) the leading ends of theprojecting pieces 47 inwardly. Therefore, the displacement of the innerfin can be prevented certainly.

Third, since each of the long sides 40 a, 40 b is provided with two ormore locating parts each having the projecting piece 47 and the recess48 to be mated each other, it is possible to improve the positioningaccuracy between the metal plates 40A, 40B furthermore. Additionally, itis possible to prevent the displacement of the inner fin.

Further, as for the modification of FIG. 14 of the first embodiment ofthe invention, it goes without saying that there can be produced thesimilar operation and effects in spite of the presence of difference inthe positions of the projecting pieces 47 and the recesses 48 on thelong sides 40 a, 40 b.

[2^(nd). Embodiment]

The second embodiment of the present invention will be described below.FIG. 15 shows the second embodiment of the present invention. In thisembodiment, elements identical to those in the first embodiment will beindicated with the same reference numerals, respectively. Additionally,overlapping descriptions in terms of constitution and effect of theelements are eliminated.

The second embodiment differs from the first embodiment in that a“top-and-back” inversion axis Y for a metal sheet 140A (140B) is acenter line extending along the longitudinal direction of the sheet 140A(140B) (i.e. a center line for dividing the sheet 140A into two equalparts in the direction perpendicular to the longitudinal direction) andthe projecting pieces 47 are arranged in symmetry with the recesses 48about the top-and-back inversion axis Y Additionally, according to thesecond embodiment, the assembly of the metal sheets 140A, 140B isprovided, on each of the short sides 40 c and 40 d, with two locatingparts each having the projecting piece 47 and the recess 48 inengagement and also provided, on each of the long sides 40 a and 40 b,with one locating part having the projecting piece 47 and the recess 48in engagement, which is different from the first embodiment.

According to the second embodiment, it should be noted that the metalsheets 140A, 140B are respectively provided, around their outercircumferential edges, with the projecting pieces 47 projecting towardthe reverse side of each metal sheet and the recesses 48 allowinginsertion of the projecting pieces 47 and that the locating parts eachhaving the projecting piece 47 and the recess 48 in combination areprovided on the sides 40 a, . . . and 40 d of each metal sheet 140A(140B), respectively. Therefore, the operations and effects are similarto those of the first embodiment.

Moreover, it is noted that, except the projecting pieces 47 and therecesses 48, the metal sheet 140A is shaped so as to be symmetrical tothe metal sheet 140B about the top-and-back inversion axis Y and thatthe projecting pieces 47 are arranged in symmetry with the recesses 48about the top-and-back inversion axis Y Therefore, it is possible toform the metal sheet 140A and the metal sheet 140B of identicalconfigurations. Thus, in spite of the provision of the projecting pieces47 and the recesses 48 in order to improve the assembling accuracy, itis unnecessary to prepare metal sheets of difference configurations,whereby the rise in manufacturing cost can be avoided.

Noted that, due to two locating parts on each of the long sides 40 a, 40b of the metal sheet 40A (40B), the first embodiment is superior to thesecond embodiment in view of the positioning accuracy of the metalsheets and the prevention of displacement of the inner fin aftercrimping the projecting pieces.

[3^(rd). Embodiment]

The third embodiment of the present invention will be described below.FIG. 16 shows the third embodiment of the present invention. In thisembodiment, elements identical to those in the first embodiment will beindicated with the same reference numerals respectively and theiroverlapping descriptions are eliminated.

The third embodiment differs from the first and second embodiments inthat a metal sheet 240A is shaped so as to be symmetrical to anothermetal sheet 240B about two “top-and-back” inversion axes X and Y andthat the projecting pieces 47 are arranged in symmetry with the recesses48 about the top-and-back inversion axes X and Y.

According to the third embodiment, since one metal sheet 240A (240B) maybe reversed about either one of the top-and-back inversion axes X and Yin order to be the other metal sheet 240B (240A), the third embodimentis superior to the first and second embodiments in terms of itsversatility. Noted that the inner fin is not shown in FIGS. 14 to 16.

In summary, according to the present invention, there are provided aplurality of locating parts on the respective sides of the outercircumferential edges of metal sheets in pairs, wherein each of thelocating part has a projecting piece and a recess that engage with eachother when one metal sheet is reversed to overlap on the other metalsheet. That is, owing to the provision of the locating parts, theassembling accuracy of the metal sheets is so improved as to make theirweld smaller, whereby it is possible to make the heat exchanger thin.

Moreover, according to the present invention, each metal sheet is shapedso as to have a symmetrical configuration about a “top-and-back”inversion axis (X, Y) or “top-and-back” inversion axes (X and Y) andthereupon, the projecting pieces are arranged in symmetry with therecesses about the top-and-back inversion axis (axes). Therefore, it ispossible to form the pair of metal sheet of identical configurations.Thus, in spite of the provision of the projecting pieces and therecesses in view of the improvement in assembling accuracy, it isunnecessary to prepare metal sheets of difference configurations,whereby the use in manufacturing cost can be avoided.

Finally, it will be understood by those skilled in the art that theforegoing descriptions are nothing but three embodiments of thedisclosed heat exchanger and therefore, various changes andmodifications may be made within the scope of claims.

1. A heat exchanger, comprising: a heat exchanging part includinglaminated tubes each of which has a pair of metal sheets joined to eachother, each of the tubes having heat exchanging passage formed thereinto extend along the longitudinal direction of the tube, and cylindricaltank parts formed at both ends of each heat exchanging passage toproject from a main body of the tube, the cylindrical tank parts of theadjoining tubes connected with each other in communication with eachother, wherein the metal sheets have at least one top-and-back inversionaxis about which one metal sheet is in inverse relation to the othermetal sheet, and wherein each metal sheet has a plurality of projectingpieces formed on the outer circumferential edge of the metal sheet so asto project toward a mate to the metal sheet and a plurality of recessesformed on the outer circumferential edge of the metal sheet so as toallow the projecting pieces to be inserted thereinto respectively, theprojecting pieces being respectively arranged symmetrically to therecesses about the top-and-back inversion axis, thereby the projectingpiece and the recess constituting a locating part when the metal sheetsare mated, the locating parts are provided on at least respective sidesof the metal sheet, respectively.
 2. The heat exchanger of claim 1,wherein the top-and-back inversion axis comprises a center line of themetal sheet in a longitudinal direction of the metal sheet.
 3. The heatexchanger of claim 1, wherein the top-and-back inversion axis comprisesa center line of the metal sheet in a direction perpendicular to alongitudinal direction of the metal sheet.
 4. The heat exchanger ofclaim 1, wherein the laminated tubes constitute a pair of heatexchanging parts which are arranged side by side.
 5. The heat exchangerof claim 1, further comprising an inner fin which is disposed in theheat exchanging passage formed in the tube, wherein the projecting piecein at least one of the locating parts has a dimension in which a leadingend thereof can pass through the recess at mating.
 6. The heat exchangerof claim 5, wherein the projecting pieces in the locating partsallocated on at least opposing sides of the metal sheets have adimension in which respective leading end thereof can pass through therecess at mating.
 7. The heat exchanger of claim 5, wherein the metalsheet has a substantially rectangular shape in plan view, and theprojecting pieces in the locating parts allocated on both long sides ofthe rectangular-shaped metal sheet have a dimension in which respectiveleading end thereof can pass through the recess at mating.
 8. The heatexchanger of claim 5, wherein the projecting pieces in the all locatingparts have a dimension in which respective leading end thereof can passthrough the recesses.
 9. The heat exchanger of the claim 1, wherein themetal sheet has a substantially rectangular shape in plan view; and twoor more locating parts are arranged on each long side of the metalsheet.